Gunn, Geoffrey C.
Boulder Westview Press 1990,
Buku Teks
McNair, Brian
Routledge, 1996
Buku Teks SO
Stephens, Mitchell
Coloumbia University Press , 2014
Buku Teks SO
Kothari, Rajni
Little, Brown, 1970
Buku Teks SO
by Brian S. Brooks ... [and others]
Bedford/St. Martins, 2002
Buku Teks SO